1. Field of the Invention
The present invention relates to a method of driving a shift register, a shift register, and a liquid crystal display (LCD) device having the shift register. More particularly, the present invention relates to a method of driving a shift register that may be used in an a-Si thin film transistor liquid crystal display device (a-Si TFT LCD) having a large display screen, a shift register, and a liquid crystal display (LCD) device having the shift register.
2. Description of the Related Art
The TFT LCD device is classified into amorphous-Si TFT LCD (or a-Si TFT LCD) device and a poly-Si TFT LCD device. The poly-silicon TFT LCD (or poly-Si TFT LCD) device has lower power consumption and a low price, but is manufactured through complex processes compared with the a-Si TFT LCD device. Accordingly, the poly-Si TFT LCD is used in a display device having a small display screen such as a mobile phone.
The a-Si TFT LCD device may provide a large display screen and a high yield (or high productivity), and is used in a display device having a large display screen such as a laptop computer, an LCD monitor or a high definition television (HDTV).
FIG. 1 is a schematic view showing a conventional poly-silicon thin film transistor LCD, and FIG. 2 is a schematic view showing a conventional a-Si thin film transistor LCD.
As shown in FIG. 1, the poly-Si TFT LCD device includes a poly-Si TFT pixel array formed on a glass substrate 10. A data driver circuit 12 and a gate driver circuit 14 are formed on the glass substrate 10. An integrated printed circuit board 20 is connected to a terminal part 16 by means of a film cable 18, so that the cost for manufacturing the poly-Si TFT LCD device may be reduced, the thickness of the poly-Si TFT LCD device may be reduce, and power consumption may be minimized because the data driver circuit 12 and the gate driver circuit 14 are integrated on the glass substrate 10.
However, as shown in FIG. 2, in the a-Si TFT LCD device, a data driver chip 34 is mounted on a flexible printed circuit board 32 via a chip on film (COF), and a data printed circuit board 36 is connected to a data line terminal on the a-Si TFT pixel array through the flexible printed circuit board 32. A gate driver chip 40 is mounted on the flexible printed circuit board 32 via the chip on film (COF), and a gate printed circuit board 42 is connected to a gate line terminal on the a-Si TFT pixel array through a flexible printed circuit board 40.
The a-Si TFT LCD device has an advantage in aspect of yield (or productivity), but has disadvantage in aspect of manufacturing cost and thickness.
In addition, in an a-Si TFT LCD device used for displaying an images on a large display screen having a high resolution, the gate driver circuit need to rapidly discharge electric charges accumulated (or charged) at the gate lines connected to pixels. The gate lines have a capacitive load.
However, deterioration of display quality may occur when the conventional gate driver circuit is used in the a-Si TFT LCD device having a large display screen.